Temperature Resistance of Xylanase Inhibitors and the Presence of Grain‐Associated Xylanases Affect the Activity of Exogenous Xylanases Added to Pelleted Wheat‐Based Feeds

Abstract

Cereal Chem. 91(6):572-577The addition of exogenous xylanases (EX-XYL) to wheat-based poultry feeds is a common practice today. Wheat contains xylanase inhibitors (XI) and grain-associated xylanases (GA-XYL), which could affect the action of the EX-XYL. In this study, both GA-XYL and XI activity in feeding-quality wheat were assessed. In addition, the effect of the conditions during digestion in monogastrics and the effects of pelleting at different conditioning temperatures on GA-XYL and XI were investigated. The GA-XYL activity varied between no activity and 0.821 XU/g. In contrast, the XI activity was consistently high in all wheat samples and ranged between 259 and 331 IU/g. Simulating the digestive process did not affect the activities of GA-XYL or XI. Pelleting at 85°C or higher reduced the XI activity up to 46%. GA-XYL, however, were more heat-sensitive, and their activity was reduced to 67% at 60°C. The extract viscosity increased and the release of reducing sugars decreased at higher conditioning temperatures. In addition, the net effect of EX-XYL on extract viscosity increased at higher temperatures, whereas the release of reducing sugars was not affected. In conclusion, XI affected the action of EX-XYL during the digestive process, and pelleting did not eliminate their negative effects.

Effect of supplemental phytase and xylanase in wheat-based diets on prececal phosphorus digestibility and phytate degradation in young turkeys

“…Those authors hypothesized that the accessibility of the remaining phytate would either not be restricted by arabinoxylans, or that other structures or the short retention time would not permit the sufficient degradation of the thick cell walls of the aleurone layer in wheat. Moreover, xylanase inhibitors in wheat are suspected to negatively affect the performance of exogenous xylanase (Smeets et al, 2014 ). However, as not all exogenous xylanases are inhibited, it is difficult to assess their role in the present study.…”

Interactions between the concentration of non-starch polysaccharides in wheat and the addition of an enzyme mixture in a broiler digestibility and performance trial

“…This corresponds to the study by Silva and Smithard ( 2002 ) who estimated that between 15 and 20% of the xylanase added to a rye-based feed was active in the small intestine. In addition to grain-associated xylanases, wheat also contains xylanase inhibitors, which are also believed to be still active in the small intestine (Smeets et al, 2014b ). In the latter study, it was observed that the xylanase inhibitors were not affected by the in vitro simulation of intestinal conditions.…”

“…Ileal viscosity was determined at 40°C using a Brookfield cone and plate viscometer. For the estimation of xylanase inhibition activity, the supernatant was diluted 2 times with sodium acetate buffer (pH 5.0, 0.025 M) and the assay was performed as described by Smeets et al ( 2014b ). Xylanase activity in the intestinal samples was evaluated by diluting the supernatant 10 times (in sodium acetate buffer, pH 5.0, 0.1 M) and adding a Xylazyme AX tablet (Megazyme International, Bray Co. Wicklow, Ireland) to 1 mL of diluted digesta sample.…”

Microbial xylanases and their inhibition by specific proteins in cereals

“…Levels of XIs can be a serious problem in different industrial applications in which the addition of exogenous xylanases affects the final quality of products (Dornez et al, 2011;Smeets et al, 2014). The high content of XIs in certain cereals reduces the xylanase efficiency in bread making, and a higher enzyme dosage should be used (Dornez et al, 2011).…”

“…Krogh Madsen et al (2018) observed that broilers fed with wheat containing the highest xylanase inhibitory activity resulted in the lowest growth rates. Inhibitory activity of these proteins was not affected during the digestion process, and feed pelleting at 85 °C had no effect on their activity (Smeets et al, 2014). Similarly, xylanase inhibition makes a problem in the processing of cereals including malting and brewing (Dornez et al, 2009), gluten-strach separation (Frederix et al, 2004) and refrigerated dough (Simsek and Ohm, 2009).…”